Field of the Invention
The present invention relates to an electronic module. Moreover, the present invention relates to a method of manufacturing an electronic module.
Description of the Related Art
In the art a plurality of electronic modules are known which comprises an electronic or semiconductor chip providing some electronic functionality. The electronic chip may be arranged or placed on a substrate and may be housed or packaged by a mold compound enclosing the electronic chip.
In particular, due to the housing by the mold compound the dissipation of heat generated by the electronic chip may be an object. This is particularly true in case the electronic module forms or is part of a power module, i.e. a module adapted and intended to handle a rather high power, e.g. several orders of magnitudes higher than for electronic modules used in the field of information technology.
Such power modules are used in batteries or electro motors, e.g. in the field of electro automobiles. These batteries and electro motors are typically heavily strained or stressed in operation during the charging and discharging processes leading to a high and rapid heat generation which may be destructive for the function of the batteries and motors. Thus, the dissipation of the generated heat is an important issue to be taken into consideration when constructing or designing such power modules. For example, materials may be used for substrates of a chip mounting or when manufacturing lead frames, wherein the materials having a high thermal conductivity. Additionally, a heat conductive material can be used as a top layer or outer layer of the electronic module in order to provide a large contact area or interface to the environment which may function as a heat sink for the module or package.
In order to improve the heat dissipation heat sinks may be provided on both main surfaces of the power module. The heat sinks are thermally coupled to the semiconductor chip wherein one heat sink may be used for cooling one side of the chip while the other heat sink is in thermal contact to the other side. The heat sinks in turn may be thermally coupled to the outside or environment by air convection or liquid cooling.
In particular, the front side or front surface of the semiconductor chip has to be cooled. Typically for conventional electronic modules or packages the front side of the semiconductor chip is thermally contacted by bond wires or clips in addition to the mold compound leading to a local discharge of the heat due to the greatly different heat conductivity of the mold compound and material of the bonding or clips.
FIG. 3 shows a cross sectional view of a conventional power module 300 comprising a printed circuit board (PCB) or direct copper bond substrate (DCB) 301 having a semiconductor chip (not shown) arranged on it. Onto the PCB 301 and/or the chip a spacing element or spacer 302 is soldered via a solder layer 303. The other side of the spacing element 302 is connected, e.g. soldered by a further solder layer 304, to a DCB 305, i.e. a ceramic board covered by a respective copper layer on each main surface of the ceramic board. The power module is then housed by a mold compound 306 which contacts the spacing element 302 at least at side portions of the same and further may cover at least portions of the DCB and/or the substrate. The mold compound or component enables that the semiconductor chip is protected from external influences and on the other side may help to homogenize mechanical stress of the module or package.
In order to increase the heat dissipation of the electronic module in addition to the heat dissipation of the front side of the electronic chip via the spacing element and the DCB the back side of the electronic chip may be connected to a heat sink as well which is formed on the back side of the substrate.
While the described electric module may exhibit good heat dissipation there may still potential room to provide improved electronic modules.